Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Print current date and time in a file

Posted on 2004-04-16
7
665 Views
Last Modified: 2010-04-15
Hi,

My C program printing data in a file. Now, I need to add current date and time in a specific format. How would I do it? Is there any library function for that?

Here is what I print in a file:

fprintf(outfile,"id=1234\n");
fprintf(outfile,"frequnecy=34000\n");
fprintf(outfile,"name=michelle\n");

Now, I need to add current date and time in yymmdd hh:mm format.

forexample:

fprintf(outfile,"namedatetime=michelle date time\n");

So, it should print in a file like this (current date & time)

namedatetime=michelle 040416 10:47

Name (michelle) is constant, so don't need to worry about it. I will put michelle in print statement .

I will be really appreciated if you can help me in this.

Thanks,
John
0
Comment
Question by:John22
  • 3
  • 3
7 Comments
 
LVL 12

Expert Comment

by:stefan73
ID: 10843016
Hi John22,
Use strftime:

 #include <time.h>

     size_t strftime(const char *s, size_t  maxsize,  const  char
     *format, const struct tm *timeptr);


Cheers,
Stefan
0
 
LVL 12

Expert Comment

by:stefan73
ID: 10843055
Here is an example:

#include <time.h>

time_t now;
char timebuf[256];

now=time(0);
strftime(timebuf,"%y%m%d %H%M",localtime(now));

fprintf(outfile,"namedatetime=michelle %s\n",timebuf);


0
 
LVL 22

Accepted Solution

by:
NovaDenizen earned 100 total points
ID: 10843151
#include <time.h>

....

time_t now_secs;
struct tm now_breakout;
char buf[1024];
time(&now);
now_breakout = *(localtime(&now)); // or use localtime_r
strftime(buf, sizeof(buf), "%g%m%d %H:%M", &now_breakout);
fprintf(outfile, "namedatetime = michelle %s\n", buf);

Check the strftime man page if you want to change the format string.  For instance, if you want to avoid y2k issues and use a 4-digit year instead, replace the "%g" with "%G"


0
Salesforce Made Easy to Use

On-screen guidance at the moment of need enables you & your employees to focus on the core, you can now boost your adoption rates swiftly and simply with one easy tool.

 
LVL 12

Expert Comment

by:stefan73
ID: 10843200
> strftime(timebuf,"%y%m%d %H%M",localtime(now));

should read

> strftime(timebuf,"%y%m%d %H%M",localtime(&now));

...as localtime expects a pointer.
0
 
LVL 22

Expert Comment

by:NovaDenizen
ID: 10843346
There's a mistake in my format fields.  The %g and %G give you the ISO 8601 bizarro year instead of the calender year, which you get through %y and %Y.  
0
 

Author Comment

by:John22
ID: 10844309
Thanks stefan73 and NovaDenizen.

I tried NovaDenizen code, but I got error. After I chaged time_t now_secs to time_t now and it worked fine.

I also tried stefan73. I also got error, but can't figure out. Here is the error:

cc -i test.c
"test.c", line 210: warning: improper pointer/integer combination: arg #1
"test.c", line 210: warning: improper pointer/integer combination: arg #2
"test.c", line 210: warning: argument #3 is incompatible with prototype:
        prototype: pointer to const char : "/usr/include/time.h", line 86
        argument : pointer to struct tm {int tm_sec, int tm_min, int tm_hour, int tm_mday, int tm_mon, int tm_year, int tm_wday, int tm_yday, i...
"test.c", line 210: prototype mismatch: 3 args passed, 4 expected
cc: acomp failed for test.c

Here is line 210:

strftime(timebuf,"%y%m%d %H%M",localtime(&now));

Thanks again.
John

0
 
LVL 22

Expert Comment

by:NovaDenizen
ID: 10844526
Don't forget to change my %g to %y.  It may give you the right answer now, but as soon as the financial year changes over it will give you the wrong answer.
0

Featured Post

Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
C dll call freezes 5 107
SCANF - LIMIT THE NUMBER OF CHARARACTERS 1 66
Grammars for C C++ and java 1 131
What is atomic operation? 6 65
An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control.  For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…
Preface I don't like visual development tools that are supposed to write a program for me. Even if it is Xcode and I can use Interface Builder. Yes, it is a perfect tool and has helped me a lot, mainly, in the beginning, when my programs were small…
The goal of this video is to provide viewers with basic examples to understand and use structures in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use switch statements in the C programming language.

829 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question